A wide variety of semiconductor devices are used as basic electronic building blocks to form electronic devices from computers to cellular telephones, home entertainment systems, and automobile control systems. Other devices use semiconductors for purposes not related to computing or processing power, such as audio amplifiers, industrial control systems, and for other such purposes.
Modern semiconductors are typically based on silicon, with various elements doped to change their electrical properties. For example, doping silicon with phosphorous creates a surplus of electrons resulting in n-type semiconductor material due to the fifth valence electron not present in silicon, which has only four valence electrons. Similarly, doping silicon with boron creates p-type silicon having a surplus of “holes”, or an absence of electrons, because boron has only three valence electrons which is one fewer than silicon.
When n-type and p-type silicon are in contact with one another, electricity flows in one direction across the junction more easily than in the other direction. More complex configurations of n-type and p-type material can be assembled to form various types of transistors, integrated circuits, and other such devices.
But, the performance of certain semiconductor devices is limited by the properties inherent in the semiconductor materials used. For example, a processor's speed is limited by the amount of power that can be dissipated in the transistors and other devices that make up the processor integrated circuit, which can literally melt if operated too fast. Reduction in size is also limited, because as more transistors dissipating a certain amount of power are packed into a smaller area, the amount of heat dissipated in a certain area increases. Even simple devices such as diodes used in high-frequency, high-power applications suffer from power limitations, since the physical size of an individual transistor or diode is typically very small.
Semiconductor devices enabling greater power dissipation and higher semiconductor device densities are desirable to provide higher performance, smaller electrical devices.